Electric meter.



No. 645,67l. Patented Mar. 20, [900. E. w. mp5, in. 'ELEOTRIC METER.

(Application filed Dec. 20, 1899.) (No Model.)

Jnventor.

EiclwinWRiee jr. A

b5 I Au UNITED STATES Fries,

PATENT EDWIN w. Rica, is, or sciiEnEoTADY, saw YORK, ASSIGNOR To THE GENERAL ELECTRIC COMPANY, OF NEW YORK;

ELECTRIC'NIETER'.

SPECIFICATION smite part of Letters Patent No. 645,671, data Matt 20, 1900.

Application filed December 20, 1899. Serial N01 740,978; (No model.)

To all whom, it may conceive: I

Be it known that I, EDWIN WV. RICE, Jr., a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Electric Meters, (Case No. 1,272,) of which the following is a specifica tion.

This invention relates to electric meters.

It is common to provide electric meters, particularly those of the Thomson recording wattmeter type, with an auxiliary field-magnet coil in the armature-circuit to provide a starting torque sufficient to overcome the friction of the parts in starting, so that the recording-dial may give a true measure of the current consumed by thetranslating devices fed through the meter. In meters provided with this starting-coil, however, it has been noticed that especially when the meter is installed at a point where there is jarring or Vibration the meter is maintained in slow operation when no translating devices are drawing current, a result due to the weak torque afiorded by the armature and starting field-magnet coil, which is at all times in circuit, being in shuntto the translating devices. The vibration reduces the friction on the bearings and permits a slow creeping of the armature, which causes the recording device to register when no current is being used by the consumer,

It is the object of myinvention to overcome this difficulty.

In carrying out my improvements I provide means for periodically cutting down the torque of the armature during each revolution thereof, thus providing, in effect, a dead point or points at which the creeping of the meter will be arrested when the main fieldmagnet coils are not energized or, in fact, when no translating devices are consuming current. A convenient way of providing these points of weak torque is afforded byintroducing at suitable points on thearmaturewinding a demagnetizing-coil to reduce the magnetizing value of the armature-current at determinate points of the air-core, by which the armature may creep only for a part'of a single revolution, and when it arrives at the dead point the field magnet forces of the starting-coil will be in substantial balance on the two sides of the armature and the latter will be arrested until the translating device's shall have been cut in and the main field'- magnet coil energized, when an increased torque is produced and the armature shifted past the dead-point and maintained in con tinuous rotation so long as the translating de-' vices are in service.

My invention therefore consists in providing the rotary element of a meter-motor with a point or points of decreased magnetization to afford a dead-point-to arrest the operation of the motor under the normal bias toward rotation when the translating devices are' not in service.

It comprises also a meter-motor the rotary element of which is provided with one or more demagnetizing-coils.

The features of novelty will be more specifically pointed out hereinafter and will be more definitely indicated in the claims In the accompanying drawing, which dia grammaticallyillustrates my invention, 1 1 represent the main field-magnet coils of a me tor-motor of thewell-known Thomson record ing wattm'eter type, and 2 represents the ar mature thereof. These wattmeters are provided with magnetic circuits constituted of air-cores, the armature being provided with a damper against rapid movement, consisting of a conducting-disk rotating within the field of permanent magnets. The main field-mag net coils are in series relation to the translating devices, represented in-the diagram as lamps at 3, though of course they may be translating devices of any other character. The armature is in a shunt-circuit across the translating devices, including a resistance at, and

the armature with a dead point or points, and.

preferably two. This may be effected in various ways, as by reducing the number of ampere-turns at suitable points in the armature-windin g by eliminating one or more coils. I prefer, however, to provide the armature with two demagnetizing-coils symmetrically related with respect to its axis, by which the magnetizing value at two opposite diametrical points is out down at those points.

When the translating devices are cut out and the main coils 1 1 are not drawing current, the meter can creep only for a part of a single armature revolution until the coils of reduced magnetization come into substantially-symmetrical relation 'to the starting field-magnet coil, of which the torque will be insufficient to shift the armature over the deadpoints, and the meter-motor willbearrested. Two such coils are indicated at 6 6, the connections with the correspondingcommutator-segments being led through two differential coils, as shown in the drawing, in symmetrical relation to y the armature coire. As ,willbe evident from the diagram, when the commutator-segments 7 '7 come under.

the brushes the coils 6 6 will be demagnetized and will be in substantially-5ymmetrical relation to the field-magnetcoils 5 5? and will, cut down the torque of the motor sufficiently,

to check it at these points and stop its creep ing. When the commutator-segments; are moved away from the brushes, the demagnet: izing-coils are cut outand the motor operates with constant torque. So long as the main field-magnet coils 1 1 are in actionithis reduction of torque is insufficient to check the rotation of the armature.

means for establishing a dead-point to new tralize the value of said coil during each revolution of the armature.

3. An electric meter comprising a field-ma net circuit in series with the translating-devices, an armature-circuit in shunt thereto, an auxiliary starting-coil on the field-magnet in series with the armature, and means for neutralizing the efiect of one or more armature-coils at determinate points 1 in the path of rotation of the armature.

4. An electric meter com prising an operating-motor, afield-magnet coil in series with the translatingdevices, an armature in shunt relation thereto, an auxiliary starting-coil in circuit with the armature, and one or more demagnetizing-coils on the armature cut in when its commutator-segment engages its brush.

5. In an electric motor, means for establishing an opposing or neutralizing magneto,- motive force in the armature atdefinitearmature, positions.

In witnesswhereof I have hereunto setmy hand this,18th day of December, 1899.

EDWIN W. RICE, JR. Witnesses:

BENJAMIN, B. HULL, MABEL E. J ACOBSON. 

